As reported by Kotaku, this spin-off is a joint effort between Respawn, EA, and Nexon. It appears to be a free-to-play affair and it will premiere in South Korea for a "Frontier Test" from 15th-21st December.

There's no word on an international release, and based on the footage below, it appears to be based more on the first Titanfall than its sequel. It's also noticeably less pretty.